In recent years a number of prostheses have been developed for deployment in body lumens to maintain the patency of a vessel or organ following a mechanical dilatation procedure. Typically, a guide wire is routed to the area to be treated. A dilatation device, usually a balloon catheter, is then inserted transluminally along the guide wire to the site of the passage and inflated to expand the vessel. The balloon catheter is then withdrawn and a delivery system carrying an expandable prosthesis is delivered to the site of the former blockage by inserting it transluminally along the guide wire. The delivery system is then actuated to deploy the prosthesis, thereby retaining the lumen patent. The insertion of both catheters to the site of the blockage or narrowing is monitored using fluoroscopy or dye techniques.
For example, percutaneous transluminal angioplasty (PTA) is commonly used today as an alternative treatment to traditional coronary artery bypass grafting. Typically, such procedures involve the insertion of the balloon catheter within a coronary artery, and dilation of the balloon to crack plaque lining the artery, thus increasing the diameter of the artery and restoring flow therethrough. It is common practice to then deploy a vascular prosthesis, such as the Palmaz Stent.RTM. sold by Johnson & Johnson Interventional Systems, Inc., to maintain the expanded diameter of the vessel. That stent comprises a slotted metallic tubular member that is plastically deformed using a balloon catheter to maintain the patency of the vessel, and is described in U.S. Pat. No. 4,739,762.
Similar methods and apparatus are known for dilating other body organs, such as the urethra, in response to blockages or narrowing caused, for example, by hypertrophy of the prostate gland. Rosenbluth U.S. Pat. No. 4,672,128 describes a balloon deployable prosthesis which is expanded to both dilate the urethra and to simultaneously implant the prosthesis.
A drawback of many of the previously known dilatation and prosthesis delivery systems is that they require either. the use of two separate catheters, as in the Palmaz system, or cannot adequately expand the body lumen during a simultaneous dilatation and prosthesis delivery step. In the two-catheter systems, a first catheter is required for dilating the vessel, and a second catheter is required for delivering the prosthesis. Moreover, the clinician must take care when inserting the prosthesis delivery system to ensure that the prosthesis is properly aligned with the portion of the body lumen dilated during the dilatation step of the procedure. Otherwise, the prosthesis may be delivered to an incorrect location within the body lumen, and the unsupported portion of the vessel may quickly restenose. With single catheter, single step systems, such as described in the Rosenbluth patent, it is not possible to fully dilate the vessel prior to, and separately from, the step of delivering the prosthesis.
It accordingly would be desirable to provide a single catheter arrangement for both fully dilating the body lumen and for delivering the prosthesis to the affected area, so as to reduce the cost and complexity of previously known procedures.
It also would be desirable to provide a combined dilatation and delivery system that would enable a clinician to reduce the time required to perform the procedure, by eliminating the need to insert and withdraw multiple catheters along the guide wire.
It further would be desirable to provide a combined dilatation and prosthesis delivery system that would enable the clinician to separately deploy the prosthesis after the dilatation procedure without requiring intermediate movement of the catheter, thereby ensuring that the prosthesis is delivered to the correct location within the body lumen.